Alternator issues

So, I went out mudding the other day, nothing to unusual. Drove away fine. Took a 100 mile drive, and on the return trip, check gauges light comes on and the voltmeter needle drops. I barely make it home as my headlights were about as bright as candles. So, I figure, alternator, great. I pulled the alternator, tested it, and it tested fine. So I bolted it back in, started the Heep and voltage was sitting right at 13.7. However, my voltage will drop intermittently and kick back on. I noticed that when it does not work, by tapping and pulling on the little black box bolted to the back of my nippondenso 90hs alternator, that I could hear it kick back on, and sure enough all is well. So, I assume that the box needs replacement. I have been lead to believe that this is the external voltage regulator. Regardless of what it is, WHERE DO I FIND ONE?!?!

Just take it apart and clean it out with electrical cleaner.

Note location of alternator. Relocate alternator to a higher position or stay out of mud puddles and water crossings (Yeah, like that is going to happen!).

Do a search here and there are a number of threads on what happened to yours, and on relocation of the alternator.